Re: [Qemu-devel] [PATCH for-2.13] pc-bios/s390-ccw: Increase virtio timeout to 30 seconds

[Thomas Huth]

On 29.03.2018 12:03, Christian Borntraeger wrote:
> 
> 
> On 03/29/2018 11:37 AM, Thomas Huth wrote:
>> The current timeout is set to only three seconds - and considering that
>> vring_wait_reply() or rather get_second() is not doing any rounding,
>> the real timeout is likely rather 2 seconds in most cases. When the
>> host is really badly loaded and we run the guest in TCG mode instead
>> of KVM, it's possible that we hit this timeout by mistake. So let's
>> increase the timeout to 30 seconds instead to ease this situation (30
>> seconds is also the timeout that is used by the Linux SCSI subsystem
>> for example, so this seems to be a sane value for block IO timeout).
> 
> I have never seen this, but cant this also with KVM (e.g. host paging
> and the swap disk is busy for some seconds).

Sure, I even assume that Lukáš might have hit this with KVM, and not
with TCG. It's just a little bit more unlikely there.

> Wouldnt it also qualify for 2.12?

Yes, I was just not sure whether we want to rebuild the s390-ccw.img
just because of this ... I'd like to leave that decision to you and
Cornelia.

 Thomas